Off topic:Best control in RNAseq for homozygous zebrafish mutant in transgenic background

Question

[mgoi]

What is the best control in RNAseq analysis for an homozygous mutant in transgenic background? (for zebrafish)

Should it be an heterozygous mutant in the same transgenic background? Could it be a regular transgenic or also a wild-type non transgenic?

Thanks!